1. Field of the Invention
This invention relates to a bowstring apparatus which permits the modification of a conventional archer's longbow, including a recurve bow, to provide for a mechanical advantage resulting in less force to draw the bow to a loaded position and to hold the drawn bow in a loaded position.
2. Description of the Prior Art
Presently the crossbow, longbow and compound bow are used in archery. The crossbow is heavy, cumbersome and awkward to load. However, once loaded an archer can take steady aim and fire the bow by a trigger means making it a relatively accurate bow.
The longbow which is lighter and easier to load than the crossbow, propels an arrow a greater distance than the crossbow. The longbow can also be fired with a faster rapidity than the crossbow. The longbow, however, requires a lot of force to draw and to hold in a drawn or loaded position, therefore accuracy falls off the longer the drawn position is held.
The compound bow utilizes the advantage of the cross bow by permitting a drawn position to be held without the force necessary to draw the bowstring into a loaded position while being lighter and less cumbersome than a crossbow. However, the compound bow is relatively heavy, awkward and noisy to use compared to the longbow. Its present popularity is based upon its ability to be more accurate than the longbow since it requires less force to maintain in the drawn position and therefore is easier to aim. This advantage is most notable where the archer maintains a drawn position waiting for his quarry to come into range.
The prior art uses a combination of eccentrically mounted pulleys, eccentric wheel assemblies and rotating lever assemblies mounted on the bow limbs to obtain a mechanical advantage permitting the use of less force to draw and to hold the bow in a loaded or drawn position than would be required without the above apparatus.
One prior art patent teaches a compound bow apparatus which utilizes cam members eccentrically mounted on the bow limb tips. The cam comprises a planar member which includes a main body section which has an outwardly extending and curved lever or hook section which projects forwardly of the plane of the main body. The bowstring is securably attached to each distal end portion of the hook section. Tension cables are securably attached to the main body section and extend to the opposite cam pivot shaft where they are anchored. Upon tensioning the bowstring, the bowstring is released from each hook section with contemporaneous rotational tension upon the tension cables.
Another patent teaches a compound bow which utilizes a pair of levers rigidly affixed with a pulley whereby tensioning the bowstring causes the synchronizing cable to synchronize the position of each of the levers which also are connected to the bowstring.
Another patent teaches a compound bow with eccentric wheel assemblies. The wheel assemblies include a bowstring wheel, a first take up wheel and a second take up wheel. The second take up wheel is secured to the bowstring wheel and includes a peripheral groove which is aligned with the groove of the first take up wheel. When the bow is drawn the bowstring is received in a groove of the second take up wheel. The characteristics of the bow are changeable by substituting various shapes of the second take up wheel.
Another patent disclosure teaches limb mounted eccentric pulleys in a compound bow where the drawstring wraps around the primary pulleys and tension cables wrap around secondary pulleys. When the bowstring is tensioned, the bowstring unwraps from the primary pulleys causing the pulley assemblies to rotate. Simultaneously tension cables wrap around the secondary pulley causing the limbs to flex. This combination is said to result in a greater amount of stored energy in the bow when drawn.
Another prior art disclosure teaches an archer's bow with rotatable rocker arm members attached to the limbs of the bow. The rocker arm members further comprise a pulley integrally attached to the rocker arms. The pulleys insure simultaneous rotation of the rocker arms when the bowstring is drawn. A bowstring connects the rocker arms and an elastic device also connected to the rocker arms resists rotation of the rocker arms. The pulleys insure substantially equal but opposite angular displacement of the rocker arms.
Another prior art disclosure teaches a device for retaining a compound bow in a partially drawn position. The object of the invention is obtained by using a ratchet means which holds a compound bow in a partially drawn position and releases its hold as the bow reaches a fully drawn condition of the bow.
It is a primary objective of this invention to provide an apparatus which overcomes the aforementioned difficulties of the prior art devices and provides an improvement which is a substantial contribution to the advancement over the archer's bow art.
It is an object of this invention to provide a bowstring apparatus which is readily attachable to a conventional longbow including a recurve bow.
It is a further object of this invention to provide a bowstring apparatus that greatly increases the accuracy and greatly reduces fatigue in operation of the longbow or recurve bow.
It is a further object of this invention to provide a bowstring apparatus which does not appreciably twist the bow limb tips and can be strung on a conventional longbow or recurve bow.
It is a further object of this invention to provide a bowstring apparatus which may be readily strung on a conventional bow to enable the bow to be held in a loaded position yet does not require that the apparatus be mounted on split limb tips as required with conventional compound bow apparatus.
It is a further object of this invention to provide a bowstring apparatus which allows for the modification of a longbow or recurve bow to permit the storage of energy in the bow structure thereby limiting the amount of force the archer is required to hold the bow in a drawn position.
It is a further object of this invention to provide a bowstring apparatus which does not require specially designed limb tips to attach the bowstring apparatus to the bow.
It is a further object of this invention to provide a bowstring apparatus which enables a conventional longbow or recurve bow to be held in a full drawn position with less force than the draw weight of the bow.
It is a further object of this invention to provide a bowstring apparatus where the draw force diminishes beyond a certain drawn point to ease the tension on the archer's draw arm to hold in a loaded position.
It is a further object of this invention to provide a bowstring apparatus which allows for changes in the draw weight of the conventional longbow or recurve bow.
It is a further object of this invention to provide a bowstring apparatus which is easily attachable to a conventional longbow or recurve bow by "stringing" the bowstring apparatus between the upper and lower bow limb tips.
It is a further object of the bowstring apparatus to provide for changes in the draw length of the conventional longbow or recurve bow.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.